Conventional semiconductor devices are fabricated with a large number of components. For example, a single semiconductor device may include a number of structures, such as gates, junctions, interconnects and contacts formed on an active area. The active area typically resides above a bulk silicon substrate of the semiconductor device. The structures formed may be desired to be electrically isolated. For example, although interconnects are designed to electrically connect certain portions of the semiconductor device, interconnects may be electrically isolated from the other interconnects. In another example, a floating gate may be electrically insulated from the source and drain.
Semiconductor devices may experience failures, such as shorts, that arise when the semiconductor device is fabricated. Similarly, components of the semiconductor devices may fail during testing and/or operation. Hence, it may be desirable to perform failure analysis on semiconductor devices to determine if a failure occurred and if so, what type of failure has occurred, whether any of the components were affected and the location of the failure.
Certain types of failures, such as short circuits, generate heat. Hence, it may be desirable to detect such failures based upon the generation of heat. Detecting such failures based upon the generation of heat may be accomplished for semiconductor devices that have passivation layers on their surfaces. A passivation layer may refer to a layer on the surface of the semiconductor device that protects silicon structures from contamination. Failures, e.g., short Circuit, that generate heat may be detected beneath such a passivation layer because the heat will not be dissipated but localized around the source of the failure. Consequently, by detecting heat generated in a particular area of the semiconductor device, one may be able to detect and locate the source of a failure.
However, some semiconductor devices do not have a passivation layer on a surface of the semiconductor device. These types of semiconductor devices may be referred to as “unpassivated semiconductor devices.” For example, an unpassivated surface may include a surface of the semiconductor device that has been exposed by removing a portion of the bulk silicon substrate of the semiconductor device. Since an unpassivated semiconductor device has a surface that is unpassivated, heat that may be generated from a failure, e.g., short circuit, may be dissipated thereby preventing the detection of the failure.
Therefore, there is a need in the art to be able to detect heat generating failures in unpassivated semiconductor devices.